Reads the switches of the STK board, recodes the
key into the number of LEDs and displays them (key 0:
all eight LEDs are on). A rather useless program but it
demonstrates the use of the LPM command and the
ROLling and JuMPing in assembly language.

Jumps over the stack. Subroutine call not via the
regular RCALL command but by putting the jump adress
on the stack. First the return adress has to be put on the
stack, then the adress of the called subroutine. The jump
and the return are done via the RET command. Out of the
series "tricky assembly programming"!